The present invention relates to a load disconnection lock for disconnecting a load from a line when the tension on the line is less than a specific value. Particular fields of application include parachutes or paragliders, in which such load disconnection locks are used to disconnect the load from the parachute immediately after landing, so that it cannot be dragged along the ground by the parachute (e.g., by a side wind) and damaged.
Load disconnecting locks of widely different types are known. See, for example, German patent document DE-OS 25 03 936, European patent document EP 1 619 975 B1 and U.S. Pat. No. 3,028,187, in which load disconnection locks have the common feature that when they are in the activated state, they are initiated immediately after a defined limit load is undershot.
However, because of the capability of their lines to stretch, modern parachute systems can oscillate, so that the load oscillates upwards and downwards a number of times under the parachute, after the shock of its opening. At the upper reversal point of this oscillation, the tension on the line is low and, in certain cases, may even briefly disappear completely. Therefore, a load disconnection lock of a convention type would be actuated immediately in a situation such as this, and the load would fall to the ground from the height at which the parachute opened; that is, from a relatively great height.
One object of the invention, therefore, is to provide a load disconnection lock which is protected against inadvertent opening in the course of the opening shock on the parachute.
This and other objects and advantages are achieved by the load disconnection lock according to the invention, which includes a first safety device that protects the locking device of the load disconnection lock from unlocking as long as the tensile load is not less than a predefined limit value, and a further safety device, which allows the locking device to be unlocked only after a defined and adjustable delay time has elapsed.
The load disconnection lock according to the invention reacts to tension relief only after this delay time. If the limit load is undershot during this time (for example, in the course of the opening shock), then unlocking cannot take place.
This delay time is provided by a fluid-filled housing in which a piston to which the tensile load is applied is guided. The piston has a hole as a flow channel for the fluid, such that the fluid can be exchanged between two housing subareas on both sides of the piston. The piston itself is connected to a slide which releases the locking device as soon as the piston has moved through a predetermined distance within the housing. The locking device therefore cannot be unlocked until the load disconnection lock has already been subjected to a load for a certain time.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.